Dittrich U.S. Pat. No. 3,617,358 relates to the composition of mullite powders used in flame spray coating of metals and ceramics. Watson et al U.S. Pat. No. 4,039,480 describes mullite coated spherical balls used in high temperature automotive applications, such as catalytic converters. Heating is disclosed for the purpose of sintering after the application of the coating.
Jones et al U.S. Pat. No. 4,963,436 is directed to the production of mullite hollow spheres used as catalysts or in packing columns. Here again, heating is utilized for sintering after the application of the coating.
Interrante U.S. Pat. No. 4,060,654 is concerned with a method of applying aluminosilicate coatings, such as mullite, which permits the use of known high temperature oxides as coating materials. Heating is relied on after the application of the amorphous mullite.
Williams U.S. Pat. No. 4,528,038 is concerned with the use of mullite coatings in which the coating is heated and components dipped into a bath for coating the substrate. Heating follows the coating process. Williams U.S. Pat. No. 4,554,186 relates to heating the substrate material after the application of the mullite coating.